A wide variety of food and beverage products are packaged in sealed containers in a hot-filling operation in which the food or beverage is heated to a temperature typically above 170° F. (77° C.), and as high as 200° F. (93° C.), in order to achieve shelf stability. After hot-filling and sealing, the sealed containers must be cooled as quickly as possible in order to both minimize any bacterial growth inside the package and to maximize the product's shelf life.
Several methods are used for cooling the hot-filled containers, including conveying the sealed hot-filled containers through a cooling tunnel where they are sprayed with a cooling medium to cool the containers to a temperature typically less than 50° F. (10° C.). When a pressurized spray is used to cool the hot-filled containers, it is important to be sure that the closure for the container is effective in preventing the pressurized spray from migrating past the closure and into the interior of the container. Such migrating cooling medium might contaminate the container's contents, and also indicates that other substances may be capable of entering the container through the closure.
Accordingly, it is an object of the present invention to provide a method for evaluating the integrity of a closure for a hot-filled container that is subjected to a pressurized cooling spray.
It is a further object of the present invention to provide such a method that does not necessarily require that the integrity of the closure be breached to determine whether the closure effectively seals the container.